Golang : Convert decimal number(integer) to IPv4 address

Problem :

You've read the previous tutorial on how to convert IPv4 address to decimal number and store into database. However, now you want to convert the decimal value back to IPv4 address. How to do that?

Solution :

Reverse the algorithm used in the conversion to decimal number. However, to get the correct result, we need to do two bit shifting and “0xff” masking.

For example :

 package main

 import (
 "fmt"
 "strconv"
 )

 func InttoIP4(ipInt int64) string {

 // need to do two bit shifting and “0xff” masking
 b0 := strconv.FormatInt((ipInt>>24)&0xff, 10)
 b1 := strconv.FormatInt((ipInt>>16)&0xff, 10)
 b2 := strconv.FormatInt((ipInt>>8)&0xff, 10)
 b3 := strconv.FormatInt((ipInt & 0xff), 10)
 return b0 + "." + b1 + "." + b2 + "." + b3
 }

 func main() {
 // 1653276013 = 98.138.253.109

 IPv4 := InttoIP4(1653276013)
 fmt.Println(IPv4)
 }

Output :

98.138.253.109

References :

https://processing.org/reference/bitwiseOR.html

http://stackoverflow.com/questions/12130464/ip-address-conversion-to-decimal-and-vice-versa